1. FIELD OF THE INVENTION
The present invention relates to an imaging method of a nuclear magnetic resonance (NMR) imaging apparatus for medical diagnosis.
2. DESCRIPTION OF THE PRIOR ART
Nuclear magnetic resonance which was independently originated by Bloch and Purcell in 1946 has been rapidly developed since then and has become an extremely effective tool for structural analysis of an organic compound and for study of material science. An apparatus for imaging proton spin density in a section of human body using this technology of Nuclear Magnetic Resonance (hereinbelow, abbreviated as NMR) is called an NMR imaging apparatus.
In a conventional apparatus, the frequency of the rotational magnetic field is varied at regular frequency intervals, thereby performing the image reconstruction from the projection data at cross-sections of regular spatial intervals, in the same manner as in an X-ray CT scanner. Therefore, even for a demand for imaging only a Region Of Interest (hereinbelow, abbreviated as ROI) in such cases as one desires to know a change of only the region of interest after an operation prescription, the image reconstruction of the whole transverse sections has been performed, so that it has been necessary to take several minutes to measure the projection data for one sheet of picture image. In addition, there is a large possibility that a human body moves during this several minutes resulting in deterioration in the quality of a resultant picture.